BACKGROUND: There are more measurement data about knee joint at home and abroad, but few data about the northern China, especially Inner Mongolia region. Whether the posterior slope angle of tibial plateau in local area differs from that of Chinese or foreigners is rarely reported.OBJECTIVE: To measure the posterior slope angle of the medial tibial plateau in healthy Mongolia population, and to compare the differences of different measurement methods, so as to understand the anatomical characters of tibial plateau in Inner Mongolia region.METHODS: Sixty Mongolian volunteers were recruited, the 20 cm upper and under the knee joint were scanned bilaterally by GE64 row spiral CT, and the three-dimensional model of the knee was established on Mimics16.0 software, followed by processed through fairing, filling, separation and cutting. Afterwards, the angel between anterior cortical bone extension line of upper tibia (method A), tibia anatomical axis (method B), line perpendicular to the posterior cortical bone extension line of upper tibia (method C) and upper edge line of the tibial plateau was measured,respectively. The posterior slope angle of the medial tibial plateau (90°-measured angle) was obtained and compared.RESULTS AND CONCLUSION: (1) The posterior slope angle of the medial tibial plateau measured by methods A, B and C was (11.16±3.39)°, (8.60±3.29)° and (5.30±4.40)°, respectively, and the former two were similar with those reported by Wang Ye-hua and Luo Ji-wei (P > 0.05). (2) There were significant differences in the posterior slope angle of the left and right medial tibial plateau among methods (P < 0.05), but there was no significant difference between left and right sides (P > 0.05). (3) There was no significant difference in the posterior slope angle of the left and right medial tibial plateau between genders (P > 0.05). (4) These results indicate that the Mongolian population show smaller posterior slope angle of the tibial plateau, but the angle exhibits great individual difference, thereafter, an individualize scheme should be developed before osteotomy.

BACKGROUND: Whether the proximal tibial osteotomy in Mongolia populations has difference with other populations at home and abroad remains unclear.OBJECTIVE: To analyze the anatomical characters of the proximal tibial osteotomy in Mongolia populations in the northern region of China by measuring the relevant linear parameters.METHODS: Thirty-eight healthy Mongolia populations were selected, and their bilateral knee joints were scanned by CT.The original data were exported in DICOM format. Mimics software was used to reconstruct the knee three-dimensional model. The tibial data stored in STL format were imported into 3-matic software, showing the medial surface of the tibia,and 6 mm below the medial tibial plateau maintaining 7° posterior slop was subjected to total hip arthroplasty osteotomy.Subsequently, the relevant parameters were measured.RESULTS AND CONCLUSION: (1) The left tibia transverse diameter was (79.99±3.70) mm, and the right was (80.25±4.01) mm. The left anteroposterior diameter was (52.27±3.07) mm, and the right was (51.75±2.40) mm. The anteroposterior diameter of medial tibia was (55.40±2.00) mm (left), and (56.67±2.47) mm (right); the lateral was (49.84±2.78) mm (left), and (49.58±2.80) mm (right). (2) In Mongolian populations, the linear parameters showed no significant differences between two sides of the proximal tibial osteotomy (P > 0.05). The anteroposterior diameter of medial tibia was longer than that of lateral one (P > 0.05). The linear parameters of the proximal tibial osteotomy in male were significantly larger than those in female (P < 0.05). There were differences in the linear parameters of the proximal tibial osteotomy between Mongolian populations and other populations. (3)These results indicate that there are significant differences in the anatomical morphology of the tibial plateau between western and eastern countries.Besides, the geometric parameters of the tibial plateau may be different in different ethnic groups and regions. It is necessary to use the digital orthopedic technique to investigate and analyze the large sample data of different ethnic groups in different regions.